java.lang.ClassCastException: org.bukkit.craftbukkit.v1_5_R3.command. ColouredConsoleSender cannot

Hi I am want to write my own plugin but it doesnt work.
Here the Error:

Code:

[WARNING] Unexpected exception while parsing console command "check"
org.bukkit.command.CommandException: Unhandled exception executing command 'chec
k' in plugin Website API v0.1
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46)
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:18
9)
        at org.bukkit.craftbukkit.v1_5_R3.CraftServer.dispatchCommand(CraftServe
r.java:523)
        at org.bukkit.craftbukkit.v1_5_R3.CraftServer.dispatchServerCommand(Craf
tServer.java:512)
        at net.minecraft.server.v1_5_R3.DedicatedServer.an(DedicatedServer.java:
262)
        at net.minecraft.server.v1_5_R3.DedicatedServer.r(DedicatedServer.java:2
27)
        at net.minecraft.server.v1_5_R3.MinecraftServer.q(MinecraftServer.java:4
77)
        at net.minecraft.server.v1_5_R3.MinecraftServer.run(MinecraftServer.java
:410)
        at net.minecraft.server.v1_5_R3.ThreadServerApplication.run(SourceFile:5
73)
Caused by: java.lang.ClassCastException: org.bukkit.craftbukkit.v1_5_R3.command.
ColouredConsoleSender cannot be cast to org.bukkit.entity.Player
        at me.unityself.Main.onCommand(Main.java:52)
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
        ... 8 more

And here my code:

plugin.yml

Code:

name: Website API
main: me.unityself.Main
version: 0.1
author: unityself
description: This is a simple API for Payment Developer
commands:
  check:
    description: Check if everything is ok.
    permission: srmarket.check
    usage: /check

Main.java

Code:

/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package me.unityself;
 
import org.bukkit.ChatColor;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.plugin.java.JavaPlugin;
 
/**
*
* @author Florian
*/
public final class Main extends JavaPlugin {
    private Main plugin;
   
    [USER=90830440]Override[/USER]
    public void onEnable(){
        getLogger().info("Website API is activated");
        //mysql Default
        this.getConfig().addDefault("mysql.enable",false);
        this.getConfig().addDefault("mysql.server","localhost");
        this.getConfig().addDefault("mysql.port",3306);
        this.getConfig().addDefault("mysql.database","api");
        //url Default
        this.getConfig().addDefault("url.enable",false);
        this.getConfig().addDefault("url.packages","http://localhost/packages.txt");
        this.getConfig().addDefault("url.packagestype",".txt");
        this.getConfig().addDefault("url.contenttype",".con");
        //ftp Default
        this.getConfig().addDefault("ftp.enable",false);
        this.getConfig().addDefault("ftp.server","localhost");
        this.getConfig().addDefault("ftp.port",21);
        this.getConfig().addDefault("ftp.username","root");
        this.getConfig().addDefault("ftp.password","yourpassword");
        this.getConfig().options().copyDefaults(true);
        this.saveConfig();
 
    }
   
   
    [USER=90830440]Override[/USER]
    public void onDisable(){
        getLogger().info("Website API isnt activated");
    }
 
    [USER=90830440]Override[/USER]
    public boolean onCommand(CommandSender sender,Command cmd,String commandLabel, String[] args){
        Player player = (Player) sender;
        if(cmd.getName().equalsIgnoreCase("check")){
        if (args.length == 0) {
        this.plugin = plugin;
        if (!(sender instanceof Player)) {
    System.out.println("Dieser Befehl ist nur für Spieler!");
    return true;
        }
        else{
        if(this.plugin.getConfig().getBoolean("ftp.enable") == false){
        player.sendMessage(ChatColor.RED+"FTP is not enabled");
        }
        else{
        player.sendMessage(ChatColor.GREEN+"FTP is enabled");
        }
       
        if(this.plugin.getConfig().getBoolean("mysql.enable") == false){
        player.sendMessage(ChatColor.RED+"MYSQL is not enabled");
        }
        else{
        player.sendMessage(ChatColor.GREEN+"MYSQL is enabled");
        }
       
        if(this.plugin.getConfig().getBoolean("url.enable") == false){
        player.sendMessage(ChatColor.RED+"URL is not enabled");
        }
        else{
        player.sendMessage(ChatColor.GREEN+"URL is enabled");
        }
       
        player.sendMessage(ChatColor.GREEN+"Your check is done!");
        return true;
        }
        }
        }
        return false;
   
    }
}

(German)Ich freue mich auch über Beiträge auf Deutsch.(German)
And here a screenshot from my Netbeans Project:

 

unityself In Main#onCommand you immediately cast the CommandSender to a Player before checking if they're actually a Player. This causes issues when the console or a command block uses your command.

 

Code:

java.lang.NullPointerException
at me.unityself.Main.onCommand(Main.java:61)
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
... 15 more

Why is the config empty or null

Here my Java code:

Code:

 
if(this.plugin.getConfig().getBoolean("ftp.enable") == false){
sender.sendMessage(ChatColor.RED+"FTP is not enabled");
}
else{
sender.sendMessage(ChatColor.GREEN+"FTP is enabled");
}

 

Because you never assign plugin to a value. In fact, why you need such a plugin instance anyway when working in the main class?